Improvement in bridge-trusses



l. WLL. Bridge-Truss.

Patented Jne 8,1875.

JONATHAN WALL, OF WILMINGTON, OIIIO.

IMPROVEMENT IN BRlDGE-TRUSSES.

Specification forming part of Letters Patent No. Illgllli, dated J une 8, 1875 application tiled March 27, 1875.

' Fig. 2 is a side view of a modification.

lhis invention has relation to the novel construction vof a straight or arched truss for a bridge, having in View the employment, in connection with the upper and lower plates, ofthe span of an intermediate or third plate, whereby the strength of the truss is greatly increased at a comparatively inoderate addition to the weight and cost of a two-plate truss. This invention accordingly consists iu the novel arrangement of parts, andespeeially of the struts which separate and brace the plates, whereby the intermediate plateis held in position and made to combine with the outer plates in resisting general compressive sti ain.

l regard the present invention as animprovement, particularly on the bridge patented by J. and Z. \'V all, February 24, 167i, wherein is also shown a tliree-plate truss, which is adapted to resist both compressive and tensile strain.

In the present insta-nce I have avoided the use of tubular struts and the zigzag arrangement shown in said patent, and have adopted solid rods of wrought or cast iron held in place by recessed angle-blocks, through the outermost series of which-that is, the blocks resting against the inner surfaces of the outer platespass the tension-rods which hold all the members of the truss together, the innermost series of blocks being fastened to the intermediate plate in any appropriate man ner. The struts have a zigzag arrangement in relation to each pair of plates, including the intermediate plate, but their lines intersect at the middle of the intermediate plate. The latter is, therefore, supported and braced equally on both sides, and equally countersustains the outer plates and interposed members.

Referring to the accompanying drawings,A A B designate the three plates of atruss, which may be either straight or arched. b bl b2 designates L the angle block applied, re: spectively, to the upper, lower, and intermediates plates, and recessed at a to receive the ends of the diagonal struts O, which terminate at the blocks b2, from each pair of which, as a hub, they radiate. D represents the tension-bolts passing through the blocks b b1, and holding nuts d on one end.

Although I purpose using solid struts I do not coniine my claim thereto, but reserve the right to use tubular struts wherever desirable. Nor do I limit myself to, specifically, three plates, as it is obvious that more than one intermediate plate may be employed Without departing materially from the essential idea.

I claim- 'Ihe combination, in a jtruss, of the three plates A A B, short diagonal struts O, recessed Iangle-blocks b b1 b2. and tension-bolts D, said struts being arranged on lines intersecting at or near the middle of the plate A with their ends resting in the recesses a of the angle-blocks b2, and the latter arranged on opposite sides, respectively, of the plate A', Iall substantially as shown and described.

In testimony that I claim the foregoing I have hereunto set my hand Vthis 26th day of March, 187 5.

J ONATHA N IVALL.

With esses:

Trios. A. CONNOLLY, Jos. B. CONNOLLY. 

